Answer:
it will be 100 mpg
Step-by-step explanation:
because 20 times 2 gallons is 40 and 20 time 3 is 60 then 20 times 4 is 80 then 20 time 5 is 100 if you just remember your times tables for two you will get your answer all your doing is just add a 0 to two for 20
